Out of tree build

It is possible to build FBTFT out-of-tree if the prerequisites are met:

	depends on FB && SPI && GPIOLIB
	select FB_SYS_FILLRECT
	select FB_SYS_COPYAREA
	select FB_SYS_IMAGEBLIT
	select FB_SYS_FOPS
	select FB_DEFERRED_IO
	select FB_BACKLIGHT

FB_BACKLIGHT is optional

Thanks to wrobell and mweal-ed for making this happen.

Beagle Bone Black

I'm using BBB as an example.

Debian image used:

• http://beagleboard.org/latest-images
• http://debian.beagleboard.org/images/bone-debian-7.5-2014-05-14-2gb.img.xz
• username: debian
• password: temppwd

Expand filesystem

Ref: http://elinux.org/Beagleboard:BeagleBoneBlack_Debian#Expanding_File_System_Partition_On_A_microSD

$ df -h
Filesystem      Size  Used Avail Use% Mounted on
rootfs          1.6G  1.5G  3.4M 100% /

$ cd /opt/scripts/tools/
$ git pull

# ignore error message: The command to re-read the partition table failed.
$ sudo ./grow_partition.sh

# this takes a little longer than usual
$ sudo reboot

$ df -h
Filesystem      Size  Used Avail Use% Mounted on
rootfs          3.6G  1.5G  2.0G  43% /

Prerequisites

$ zgrep -E "CONFIG_SPI=|CONFIG_GPIOLIB=|DEFERRED|FB_SYS_|FB_BACKLIGHT" /proc/config.gz
CONFIG_SPI=y
CONFIG_GPIOLIB=y
CONFIG_FB_SYS_FILLRECT=y
CONFIG_FB_SYS_COPYAREA=y
CONFIG_FB_SYS_IMAGEBLIT=y
CONFIG_FB_SYS_FOPS=y
CONFIG_FB_DEFERRED_IO=y

FB_BACKLIGHT is missing, which disables the builtin FBTFT backlight handling.

Kernel headers

Ref: http://dumb-looks-free.blogspot.fr/2014/06/beaglebone-black-bbb-kernal-headers.html

Install kernel source

$ wget https://raw.github.com/gkaindl/beaglebone-ubuntu-scripts/master/bb-get-rcn-kernel-source.sh
$ chmod +x bb-get-rcn-kernel-source.sh
$ sudo ./bb-get-rcn-kernel-source.sh

I had to change EXTRAVERSION to have the modules end up in the right directory when doing make install later.

$ uname -r
3.8.13-bone50
$ cd /usr/src/linux-3.8.13-bone50/
$ sudo nano Makefile
EXTRAVERSION = -bone50

# not sure if this is needed, didn't take the time to find out
$ sudo make prepare

FBTFT

Fetch FBTFT source, build and install drivers

$ cd
$ git clone https://github.com/notro/fbtft
$ cd fbtft
$ make
$ sudo make install
# I don't know why this is needed (it has been run by the previous make command)
$ sudo depmod
# modules should end up here
$ ls -l /lib/modules/3.8.13-bone50/extra/

Load driver

# enable SPI
$ echo BB-SPIDEV0 | sudo tee /sys/devices/bone_capemgr.*/slots
BB-SPIDEV0
$ ls -l /dev/spi*
crw-rw---T 1 root spi 153, 1 Jul  2 15:01 /dev/spidev1.0
crw-rw---T 1 root spi 153, 0 Jul  2 15:01 /dev/spidev1.1
# I didn't test this with a display, only tested to see if the driver would load
$ sudo modprobe fbtft_device name=hy28b busnum=1 #gpios=reset:XX
$ dmesg | tail
<snip>
[74822.230273] graphics fb1: fb_ili9325 frame buffer, 240x320, 150 KiB video memory, 4 KiB DMA buffer memory, fps=51, spi1.0 at 48 MHz